public interface ITestEvent
{
	public delegate void TestEventHandler();
	public event TestEventHandler TestEvent;

	public int AnProperty { get; }

	public bool Test();
}

namespace Test
{
    public delegate void TestEventHandler();
    
    public interface ITestEvent
    {
        event TestEventHandler TestEvent;
    }
    
    public class testEventImplementation : ITestEvent
    {
        // C# 7 version - need to add "public" keyword to this event
        // otherwise the code does not compile
        public event TestEventHandler TestEvent;
    }
}

public interface ITestEvent
{
    public delegate void TestEventHandler();
    public event TestEventHandler TestEvent;
}
    
class TestEventImplementation : ITestEvent
{
    // C# 8 version - keeping public keyword from event in base class
    // need to scope the return type, since the type is not being
    // implemented here, instead used from the base class
    public event ITestEvent.TestEventHandler TestEvent;
}

namespace Test
{
	public delegate void TestEventHandler();

	public interface ITestEvent
	{
		event TestEventHandler TestEvent;

		int AnProperty { get; }

		bool Test();
	}
}

class TestEventImplementation : ITestEvent
{
}